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In our skies: Fond memories of NASA's Deep Space Network, Uranus

A rather unique sky show will greet sky-watchers who are willing to brave the frigid predawn skies on these late January mornings, when all five of the bright planets of our solar system are simultaneously visible.

In our skies: Fond memories of NASA's Deep Space Network, Uranus

A rather unique sky show will greet sky-watchers who are willing to brave the frigid predawn skies on these late January mornings, when all five of the bright planets of our solar system are simultaneously visible.

Jupiter rises around 9 p.m. local time and is almost overhead around 3:30 a.m.; it is followed by Mars, which rises around 1 a.m., and Saturn, which rises around 4 a.m. Finally, brilliant Venus rises shortly after 5 a.m., and tiny Mercury rises about half an hour later and sits low in the southeastern sky during the early dawn.

These five planets are all conspicuous naked-eye objects and have been known since antiquity. There is, however, a sixth planet which is visible to the unaided eye, albeit only very dimly, and thus as far as our distant ancestors were concerned it was never more than a dim and unremarkable star. This object’s planetary nature was finally discovered in 1781 by the British astronomer William Herschel, and we now know it as the planet Uranus.

Being located almost twice as far from the sun as Saturn is, Uranus has only slowly and begrudgingly given up its secrets during the 2 1/3 centuries since then. It is a giant planet significantly larger than Earth, although quite a bit smaller than Jupiter and Saturn, and is primarily made up of lightweight gaseous substances as are those two worlds.

One rather unusual feature of Uranus is that its rotational pole is tilted such that it basically rotates on its side. Up through the mid-20th century five moderately small moons were discovered orbiting around the planet. Perhaps one of the most remarkable discoveries involving Uranus came in 1977 when a team of astronomers planning to watch Uranus occult, or pass in front of, a distant star discovered that Uranus is accompanied by a system of thin rings, somewhat similar to, although much thinner and darker than, the rings around Saturn.

The majority of our knowledge about Uranus came 30 years ago this weekend when, on Jan. 24, 1986, the Voyager 2 spacecraft passed by that planet. Voyager 2 was launched in August 1977 and then made flybys of Jupiter and Saturn in July 1979 and August 1981, respectively, before being directed onward toward this much more distant world.

During its flyby of Uranus Voyager 2 revealed a visually bland world with only a few thin hazy clouds, but also detected a bizarrely oriented magnetic field and provided much information about Uranus’ atmosphere and interior structure. Voyager 2 also took dramatic photographs of Uranus’ rings and its known moons, in the process discovering 10 additional, smaller moons.

The Voyager 2 encounter with Uranus turned out to be a watershed event in this author’s life. At the time he was working as a contractor for NASA’s Deep Space Network, and was specifically tasked with providing support for the radio science phase of the encounter, i.e., the gleaning of information about the planet via its effects on the spacecraft’s carrier signal.

In particular, effects upon the signal as the spacecraft passed behind Uranus’ rings, as seen from Earth, would tell us information about the sizes of the particles in the rings, and the effects upon the signal as the spacecraft passed behind the planet itself would tell us much about the structure of the atmosphere.

The preparations for the event were enormous, and involved working 18-hours a day, 7-days a week.

Special software had to be written that would take mathematical models of Uranus’ atmosphere, as poorly known as that was, and translate these into radio frequencies that the DSN antennas had to tune-in to in order to receive the spacecraft signal, a task made considerably more complex by the fact that Voyager 2’s receiver was tone-deaf – it could only receive signals within a band 90 hertz wide – and any electrical events within the spacecraft could affect this significantly.

The hard work paid off: The encounter was a complete success. While providing real-time support for the encounter at the Space Flight Operations Facility at NASA’s Jet Propulsion Laboratory in California, this author was among the first people in the world to see the spacecraft’s radio signals when they arrived back at Earth, and, for example, was one of the first people in the world to learn that Uranus’ rings are made up of objects in the centimeter to meter size range.

Much has happened in the three decades that have elapsed since the encounter. Voyager 2 went on to an equally successful encounter with the planet Neptune 31Ž2 years later, and even now remains in contact with Earth as it leaves the solar system and heads into interstellar space. Uranus has continued on in its orbit around the sun, and currently can be found in the constellation Pisces, high in our western sky during the early evening hours.

And this author? He would leave JPL a few months later to enter graduate school, and six years later would successfully defend a Ph.D. dissertation on exoplanets, a paper which is cited regularly in all the current research being conducted in that field of study. He would also become recognized around the world for his discovery of a comet in 1995 that, two years later, became a spectacular object viewed by more human beings than any comet in history.

He would also experience the various ups and downs of life, including the raising of two sons who are now grown and on their own, travels around the world, divorce, the beginning and ending of a deep romantic relationship, and the deaths of both his parents.

But among his many memories are those of his participation in this once-in-a-life time event three decades ago. There have been no further spacecraft missions to Uranus since then, and none are under serious consideration at this time, so, for now at least, he has the satisfaction of knowing he contributed to one of the most unique scientific events in all of human history.

Alan Hale is a professional astronomer who resides in Cloudcroft. He is involved in various space-related research and educational activities throughout New Mexico and elsewhere. His web site is http://www.earthriseinstitute.org